Alkylene oxide polymerization using aluminum compounds and cyclic amidines

ABSTRACT

Polyethers are prepared by polymerizing an alkylene oxide in the presence of a starter, an aluminum compound that has at least one hydrocarbyl substituent, and a cyclic amidine. The phosphorus-nitrogen base is present in only a small molar ratio relative to the amount of starter. The presence of such small amounts of cyclic amidine greatly increases the catalytic activity of the system, compared to the case in which the aluminum compound is used by itself. The product polyethers have low amounts of unsaturated polyether impurities and little or no unwanted high molecular weight fraction. Polymers of propylene oxide have very low proportions of primary hydroxyl groups.

This invention relates to a process for polymerizing one or morealkylene oxides or copolymerizing one or more alkylene oxides with oneor more copolymerizable monomers which is not an alkylene oxide.

Alkylene oxide polymers and copolymers are produced globally in largequantities. Polyether polyols, for example, are an important rawmaterial for producing polyurethanes. Among other things, they are usedto make high resiliency, molded, or rigid foams. Polyether monols areused, for example, as surfactants and industrial solvents, among otheruses. Carbonate- and ester-modified alkylene oxide polymers also finduses in these and other applications.

Polyether monols and polyols are produced by polymerizing an alkyleneoxide in the presence of a starter compound. The starter compound hasone or more functional groups at which the alkylene oxide can react tobegin forming the polymer chains. The main functions of the startercompound are to provide molecular weight control and to establish thenumber of hydroxyl groups the polyether will have.

A catalyst is needed to obtain economical polymerization rates. The mostcommonly used catalysts are alkali metal hydroxides such as potassiumhydroxide and the so-called double metal cyanide (DMC) catalystcomplexes, of which zinc hexacyanocobaltate catalyst complexes are themost commercially important type.

Alkali metal hydroxides provide the benefits of low catalyst costs andacceptable polymerization rates. They are versatile in that theyeffectively polymerize many alkylene oxides. The product polyetherusually, but not always, has a narrow molecular weight distribution. Aparticular advantage of these catalysts is that they can be used topolymerize ethylene oxide onto an alcoholic starter. This ability isquite important industrially as many polyether polyols manufactured aspolyurethane raw materials are block copolymers made by polymerizingpropylene oxide and then ethylene oxide onto a starter compound. Thealkali metal hydroxide catalyst permits this to be done easily andinexpensively, as both polymerizations can be performed in the samevessel using the same catalyst system, without recovering theintermediate poly(propylene oxide) polyol.

Nonetheless alkali metal hydroxides have well-known drawbacks. Alkalimetal hydroxide catalysts promote a side reaction that forms unsaturatedmonoalcohols, which become alkoxylated to form unwanted monofunctionalspecies. The presence of these unwanted monofunctional species can alsobroaden molecular weight distribution. Polyols made using thesecatalysts need to be neutralized and purified to remove catalystresidues, which adds significant capital and operating expense to themanufacturing process. In addition, the product polyether tends to havea broad molecular weight distribution when made in a back-mixedcontinuous process.

DMC catalysts provide rapid polymerization rates compared to alkalimetal catalysts, even when used at very low catalyst concentrations. Inaddition, they have distinct and important advantages over alkali metalcatalysts. The DMC catalysts rarely if at all promote the side reactionthat produces monofunctional by-products, so the hydroxyl functionalityof the product is close to the theoretical value (as defined by thestarter). A second main advantage is that no neutralization step isneeded. The catalyst residues often can be left in the product, unlikethe case when alkali metal hydroxides are used as the polymerizationcatalyst. This can result in significantly lower production costs. Athird advantage is that, unlike alkali metal hydroxide catalysts, DMCcatalyst complexes produce low polydispersity polymers when thepolymerization is performed in a back-mixed continuous main reactor.

Nonetheless, the DMC catalysts have disadvantages as well. They tend toperform poorly in the presence of high concentrations of hydroxylgroups, and especially in the presence of low molecular weight startercompounds like glycerin that have hydroxyl groups in the 1,2- or1,3-positions with respect to each other. Under these conditions, thecatalysts are difficult to activate, perform sluggishly and often becomedeactivated before the polymerization is completed. This represents asignificant limitation on the widespread adoption of DMC catalysts. Itis often necessary to produce the polyether in two or more discretesteps, in which the early stages of the polymerization are conducted inthe presence of an alkali metal catalyst and, after cleaning up theresulting intermediate product, the remainder of the polymerization isperformed using the DMC catalyst. This approach requires theintermediate to be neutralized and purified (because the DMC catalyst isdeactivated by strong bases), thus re-introducing costs which theDMC-catalyzed polymerization is intended to avoid.

Another very significant disadvantage of the DMC catalysts is theycannot be used on an industrial scale to produce ethylene oxide-cappedpolyethers. Instead of adding onto the chain ends in a regular andcontrolled manner, the ethylene oxide instead tends to produce very highmolecular weight poly(ethylene oxide) polymers. Despite many attempts toresolve this problem, it has not been satisfactorily addressed, andethylene oxide-capped polyethers are almost always made at industrialscale using an alkali metal hydroxide catalyst to perform the cappingstep.

Yet another problem associated with DMC catalysts is they produce asmall amount of very high molecular weight (40,000+ g/mol) polymers. Thepresence of these polymers increases polyol viscosity, broadensmolecular weight distribution, and can also adversely affect the abilityof the polyether polyols made with DMC catalyst complexes to produceflexible polyurethane foam.

Certain Lewis acids have been evaluated as alkylene oxide polymerizationcatalysts. The Lewis acids require essentially no activation time, butbecome deactivated rapidly and therefore cannot produce high molecularweight polymers or high conversions of alkylene oxide to polymer. Inaddition, poly(propylene oxide) polymers produced by Lewis acidcatalysis tend to have a large proportion of primary hydroxyl groups.

In addition, various aluminum compounds have been described for use asalkylene oxide polymerization catalysts.

In Polym. Chem. 2012, 3, 1189-1195 there is described a propylene oxidepolymerization in the presence of a poly(propylene oxide) startercompound, triisobutylaluminum and a phosphazene base. Thispolymerization is conducted in toluene solution at 20° C. Thephosphazene base is used in large quantities, about one mole perequivalent of starter. US Published Patent Application No. 2018-0237586describes another solution polymerization of propylene oxide in thepresence of a trialkyl aluminum and a nitronium alkoxide, the latter ofwhich is described as a starter. Again, large amounts of the nitroniumalkoxide are used. High molecular weight polyethers that have a broadmolecular weight distribution are obtained.

Macromolecules 2008, 41, 7058-7063 describes a polymerization ofepichlorohydrin using a triisobutylaluminum compound and in the presenceof tetraoctylammonium bromide, at temperatures up to room temperature,and in the absence of a starter.

U.S. Pat. No. 6,919,486 describes polymerizing propylene oxide in thepresence of a polyether triol starter and an aluminum phosphonatecatalyst. Ethylene oxide capping is also described. The polymerizationsare performed in the absence of solvent and at a temperature of 110° C.

Macromolecules 1974, 7, 153-160 describes low temperaturepolymerizations of propylene oxide in bulk, in the presence ofaluminoxanes such as (C₂H₅)₂AlOAl(C₂H₅)₂ (TEDA). No starter ismentioned. Polyethers having molecular weights of 100,000 to 1 millionare obtained. J. Polym. Sci. 1973, 11, 699-712 describes using TEDA topolymerize propylene oxide in solution at 40° C., in the absence of astarter.

Diethylaluminum chloride is described as an alkylene oxidepolymerization catalyst in a solution polymerization without a starterat temperatures up to 110° C. in U.S. Pat. No. 3,029,216 and in a bulkpolymerization without a starter at 25° C. in J. Polym. Sci. 1959, 34,157-160. High molecular weight polymers are obtained.

This invention is in one aspect a method for producing an alkylene oxidepolymer or copolymer, comprising combining (i) at least one aluminumcompound containing at least one trisubstituted aluminum atom, whereinat least one of the substituents of at least one trisubstituted aluminumatom is hydrocarbyl; (2) at least one cyclic amidine; (3) at least onestarter; (4) at least one alkylene oxide and optionally (5) at least onecomonomer that is not an oxirane, and polymerizing the alkylene oxide(s)or copolymerizing the alkylene oxide(s) and optionally the comonomer toform the alkylene oxide polymer or copolymer.

The method of the invention offers several advantages, from both processand product perspectives.

Process advantages include rapid polymerization rates; the ability toalkoxylate starters that have a wide range of molecular weights, inparticular low molecular weight starters that have hydroxyl equivalentweights of 30 to 75; the ability to use significantly lower levels ofcatalyst than needed with alkali metal hydroxides, thereby reducingcosts and permitting at least in some cases the polyols to be usedwithout the need to first remove catalyst residues; the ability to usehigher URO (unreacted alkylene oxide) levels than can be used with theDMC catalyst without formation of unwanted higher molecular weightpolymers; and the ability of the catalyst to polymerize ethylene oxideuniformly. This last advantage is of great importance industrially inview of the difficulty seen with polymerizing ethylene oxide with doublemetal cyanide catalysts. The ability to uniformly polymerize ethyleneoxide permits the catalyst to be used to make oxyethylene-capped polyolsthat have high proportions of primary hydroxyl groups, and permitsoxyethylene-capped polypropylene oxide), oxyethylene-cappedpoly(butylene oxide), oxyethylene-capped polypropylene oxide-co-ethyleneoxide) and oxyethylene-capped poly(butylene oxide-co-ethylene oxide)polyols to be prepared using a single catalyst for the propylene oxide,butylene oxide, propylene oxide-co-ethylene oxide and/or butyleneoxide-co-ethylene oxide polymerization as well as the capping step.

The invention in another aspect is a polyether polyol being ahomopolymer of propylene oxide or random copolymer of propylene oxideand ethylene oxide, the polyether polyol being prepared byhomopolymerizing propylene oxide or a mixture of at least 70% by weightpropylene oxide and correspondingly up to 30% by weight ethylene oxide,based on the weight of alkylene oxides polymerized, in the absence ofany comonomer that is not an oxirane, to form the polyether polyol,characterized in that

a) the polyether has a hydroxyl equivalent weight of at least 500 up to4000 g/equivalent;

b) the polyether has a nominal hydroxyl functionality of 2 to 8;

c) the polyether has no more than 0.01 meq/g of terminal unsaturation;

d) the polyether has a polydispersity (M_(w)/M_(n)) by gel permeationchromatography of no more than 1.10;

e) the polyether contains no more than 2000 parts by million by weight(ppm) based on polyether polyol weight, of a fraction having a molecularweight by GPC of 40,000 g/mol or more; and

f) no more than 12% of the hydroxyl groups of the polyether are primaryhydroxyl groups as determined by ASTM D-4273 or equivalent method,

wherein at least 90% of the weight of the polyether is oxypropyleneand/or oxyethylene units.

In yet another aspect, the invention is a polyether polyol being apropylene oxide homopolymer or random copolymer of propylene oxide andethylene oxide, the polyether polyol being prepared by homopolymerizingpropylene oxide or a mixture of at least 90% by weight propylene oxideand correspondingly up to 10% by weight ethylene oxide, based on theweight of alkylene oxides polymerized, in the absence of any comonomerthat is not an oxirane, to form the polyether polyol, the polyetherpolyol being further characterized in a) having a hydroxyl equivalentweight of 1000 to 2500 g/equivalent, b) having a nominal functionalityof 2 to 8; c) having no more than 0.007 meq/g of terminal unsaturation;d) having a polydispersity (M_(w)/M_(n)) of no more than 1.07; and e)containing no more than 1200 ppm, of a fraction having a molecularweight by GPC (gel permeation chromatography) of 40,000 g/mol or more,wherein at least 90% of the weight of the polyether is oxypropyleneand/or oxyethylene units.

From the product standpoint, the advantages of the invention include i)low polydispersities (M_(w)/M_(n)); ii) absence of the “high molecularweight tail” that is seen in DMC catalyzed polymerizations; iii) lowformation of unwanted monofunctional species due to the isomerization ofalkylene oxide into unsaturated alcohols; and iv) when propylene oxideis homopolymerized, the production of polyethers that have very lowproportions of primary hydroxyl groups.

The aluminum compound is an aluminum compound containing at least onetrisubstituted aluminum atom. At least one, at least two or all three ofthe substituents of at least one trisubstituted aluminum atom arehydrocarbyl. Two or more of the substituents on a trisubstitutedaluminum atom may together form a ring structure.

The aluminum compound may contain 1, 2, 3, 4 or more aluminum atoms(such as up to 100, up to 50, up to 25, up to 12 or up to 5 aluminumatoms), of which at least one is trisubstituted.

A hydrocarbyl substituent may be aliphatic, cycloaliphatic, aromatic orany combination of two or more thereof, and is bonded to the aluminumatom via an aluminum-carbon bond. The hydrocarbyl substituent in somecases has up to 12, up to 6 or up to 4 carbon atoms. The hydrocarbylgroup may be, for example, a linear or branched alkyl group such asmethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl and thelike. A hydrocarbyl substitutent(s) may be unsubstituted or inertlysubstituted.

The non-hydrocarbyl substituent groups bonded to the aluminum atom(s)may be, for example, halogen, phosphonate, hydride, oxo (i.e., —O—),alkoxide or phenoxide. Two or more of the substituents on atrisubstituted aluminum atom may together form a ring structure.

Non-hydrocarbyl substituent groups bonded to the aluminum atom(s) maybe, for example, halogen, phosphonate, hydride, oxo (i.e., —O—),alkoxide or phenoxide.

A halogen substituent may be, for example, fluorine, chlorine, bromineor iodine.

An alkoxide or phenoxide substituent may have the form —O—R² or—O(—R²—O)_(z)—R²—O-Z wherein each R² is independently a hydrocarbyl orsubstituted hydrocarbyl group, z is zero or a positive number, Z ishydrocarbyl, inertly substituted hydrocarbyl, hydrogen or —AlY₂ whereeach Y is halogen, hydrocarbyl, phosphonate, hydrogen, oxo (i.e., —O—)or alkoxide or phenoxide. The alkoxide or phenoxide may include apolyether chain such as a poly(oxyethylene) or poly(oxypropylene chain).Specific examples of alkoxide or phenoxide substituents includeethoxide, n-propoxide, isopropoxide, t-butoxide, n-butoxide,isobutoxide, phenoxide, 2,6-di-t-butyl-4-methyl phenoxide,2,6-diisopropylphenoxide, 2,6-diphenylphenoxide,2,4,6-trimethylphenoxide, 4-fluorophenoxide, 4-chlorophenoxide,3,4,5-trifluorophenoxide,

wherein R⁵ is hydrogen, phenyl or C₁₋₄ alkyl and z is as before, and

Any of these substituent groups except hydride may form all or part of abridge between aluminum atoms. Thus, for example, an oxo (—O—) group maybond two aluminum atoms to from an aluminoxane. Similarly, a divalenthydrocarbon radical may be bonded to two aluminum atoms to form a bridgetherebetween, as may an —O—R²—O— diradical or a —O—(R²—O)_(z)—R²—O—diradical.

In some embodiments, at least one aluminum atom is substituted with oneor two hydrocarbyl groups, and is substituted with one or two halogen,oxo, ether, hydride or phosphonate groups. If more than one aluminumatom is present in the aluminum compound, all of the aluminum atoms maybe substituted in such a manner.

Specific examples of aluminum compounds include trimethyl aluminum,triethyl aluminum, triisopropyl aluminum, tri(n-propyl) aluminum,triisobutyl aluminum, tri(n-butyl)aluminum, tri(t-butyl)aluminum,tri(octadecyl)aluminum, dimethyl aluminum chloride, methyl aluminumdichloride, diethyl aluminum chloride, ethyl aluminum dichloride,diisobutyl aluminum chloride, isobutyl aluminum dichloride, methylaluminum di[(2,6-di-t-butyl-4-methyl)phenoxide] (Al(BHT)₂Me), dimethyl2,6-di-t-butyl-4-methylphenoxide (AlBHTMe₂), methyl aluminumdi(2,6-diisopropyl)phenoxide, dimethyl aluminum(2,6-diisopropyl)phenoxide methyl aluminum di [(2,6-diphenyl)phenoxide], dimethyl aluminum (2,6-diphenyl) phenoxide, methyl aluminumdi[(2,4,6-trimethyl)phenoxide], dimethyl aluminum(2,4,6-trimethyl)phenoxide, tetraethylaluminane, tetramethylaluminane,diisobutyl aluminum (DIBAL), isobutyl aluminum dihydride, dimethylalumimum hydride, methyl aluminum dihydride, diethyl aluminum hydride,ethyl aluminum dihydride, diisopropyl aluminum hydride, isopropylaluminum dihydride, diethyl aluminum ethoxide, ethyl aluminumdiethoxide, dimethyl aluminum ethoxide, methyl aluminum diethoxide,dimethyl aluminum fluoride, methyl aluminum difluoride, diethyl aluminumfluoride, ethyl aluminum difluoride, diisobutyl aluminum fluoride,isobutyl aluminum difluoride, dimethyl aluminum bromide, methyl aluminumdibromide, diethyl aluminum bromide, ethyl aluminum dibromide,diisobutyl aluminum bromide, isobutyl aluminum dibromide, dimethylaluminum iodide, methyl aluminum diiodide, diethyl aluminum iodide,ethyl aluminum diiodide, diisobutyl aluminum iodide, isobutyl aluminumdiiodide, and a tetraalkylaluminoxane in which each alkyl group of thetetralkylaluminoxane independently contains 1 to 6 carbon atoms.

An “inert” substituent for purposes of this invention is one that is notreactive towards hydroxyl groups, amino groups or isocyanate groups.Examples of inert substituents include, for example, hydrocarbylsubstituents, ether groups, ester groups tertiary amino groups, amidegroups, halogen and the like.

Cyclic amidines useful herein include an —N—CH═N— moiety as part of thering structure. In some embodiments, the cyclic amidine is a triazacompound having a

moiety as part of the ring structure, wherein R¹ is as defined below.

Suitable cyclic amidines include bicyclic amidines, including thoserepresented by Structure I as follows:

wherein X is CHR or NR¹, wherein each R is independently hydrogen,unsubstituted or inertly substituted alkyl (including cycloalkyl),unsubstituted or inertly substituted phenyl or a non-protic nucleophilicgroup and each R¹ is independently hydrogen, hydrocarbyl or inertlysubstituted hydrocarbyl, and m and n are each independently a positiveinteger. m is preferably 1 or 2 and most preferably 2. n is mostpreferably 1, 2 or 3.

Each R is preferably hydrogen, phenyl or lower (C₁₋₄) alkyl. When R is anon-protic nucleophilic group, it should be devoid of hydrogen atomsthat are reactive towards hydroxyl groups and isocyanate groups. Such anon-protic nucleophilic group may include, for example, a tertiaryphosphine or tertiary amino group. The nitrogen atom of an amino groupor phosphorus atom of a phosphine group may be bonded directly to acarbon atom of the ring structure. Alternatively, the amine nitrogen orphosphine phosphorus atom may be indirectly bonded to a carbon atom ofthe ring structure through some bridging group which may be, forexample, alkylene or other hydrocarbyl group. A non-protic nucleophilicgroup may take the form —(CH₂)_(y)N(R²)₂ or —(CH₂)_(y)P(R²)₂, wherein yis from 0 to 6, preferably 0, 1 or 2, more preferably 0, and each R² isindependently an alkyl group, inertly substituted alkyl group, phenylgroup, or inertly substituted phenyl group.

Specific bicyclic amidine compounds include1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD),5-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (Me-TBD)1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU),1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, where the butylgroups of the 6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene areindependently n-butyl, sec-butyl or t-butyl groups.

Other suitable cyclic amidine compounds include imidazole and imidazolederivatives, including those corresponding to Structure II:

wherein R³ and each R⁴ is independently hydrogen, unsubstitutedhydrocarbyl or inertly substituted hydrocarbyl. R³ preferably ishydrogen, alkyl, alkenyl, phenyl, or alkyl-substituted phenyl; if alkylor alkenyl R³ preferably has up to 12, up to 8, up to 6 or up to 4carbon atoms. R³ may be methyl or ethyl. Any R⁴ may be hydrogen, alkyl,alkenyl, phenyl, or alkyl-substituted phenyl; if alkyl or alkenyl R⁴preferably has up to 12, up to 8, up to 6 or up to 4 carbon atoms. R⁴may be methyl or ethyl.

Specific examples of imidazole and imidazole derivatives includeimidazole, N-methyl imidazole, N-ethyl imidazole, N-phenyl imidazole,1,2-dimethyl imidazole, 1,2-diethyl imidazole, 1,2-diphenyl imidazole,4,5-dimethyl imidazole, 4,5-diethylimidazole, 4,5-diphenyl imidazole,1,4,5-trimethyl imidazole, 1,4,5-triethyl imidazole, 1,4,5-triphenylimidazole and the like.

The polymerization is performed in the presence of one or more startercompounds. The starter compound has one or more functional groupscapable of being alkoxylated. The starter may contain any larger numberof such functional groups. The functional groups may be, for example,primary, secondary or tertiary hydroxyl, primary amino, secondary aminoor thiol. A preferred starter contains 1 or more such functional groups,preferably 2 or more of such functional groups, and may contain as manyas 12 or more of such functional groups.

In certain embodiments, the functional groups are all hydroxyl groupsand the starter does not contain primary and/or secondary amino groupsor thiol groups. In some embodiments, the starter compound will have 2to 8, 2 to 4 or 2 to 3 hydroxyl groups.

In certain embodiments, the functional groups are all primary and/orsecondary amine groups and the starter does not contain primary and/orsecondary hydroxyl groups (other than residual water) or thiol groups.In some embodiments, the starter compound will have 2 to 8, 2 to 4 or 2to 3 primary and/or secondary amine groups.

The starter compound has an equivalent weight per functional group lessthan that of the polyether product. It may have an equivalent weight of9 (in the case of water) to 6000 or more. In some embodiments, thestarter compound has an equivalent weight of 9 to 4000, 9 to 2500, 30 to1750, 30 to 1400, 30 to 1000, 30 to 500, or 30 to 250.

Equivalent weight of an alcohol or polyol is conveniently determinedusing titration methods such as ASTM 4274-16, which yield a hydroxylnumber in mg KOH/gram of polyol that can be converted to equivalentweight using the relation equivalent weight=56,100÷hydroxyl number.

Among the suitable starters are vinyl alcohol, propenyl alcohol, allylalcohol, acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate,a C₁₋₅₀ alkanol, phenol, cyclohexanol, an alkylphenol, water (consideredfor purposes of this invention as having two hydroxyl groups), ethyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, tripropylene glycol, 1,4-butane diol, 1,6-hexanediol, 1,8-octane diol, cyclohexane dimethanol, glycerin,trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol,sucrose, phenol, polyphenolic starters such as bisphenol A or1,1,1-tris(hydroxyphenyl)ethane, and the like.

Other suitable starters are amine compounds such as morpholine,piperadine, piperazine, toluene diamine (any isomer or mixture ofisomers), phenylene diamine (any isomer or mixture of isomers), ethylenediamine, diethylene triamine, higher polyethylene polyamines having upto 8 nitrogen atoms, 1,3-propane diamine, 1,2-propane diamine,1,4-butane diamine, cyclohexane diamine, isophorone diamine,bis(aminomethyl)cyclohexane and bis(3-aminopropyl) methyl amine.

Still other suitable starters are hydroxyl-terminated polyethers(including alkoxylates, especially ethoxylates and/or propoxylates, ofhydroxyl-containing and/or amine starters including those justdescribed) having hydroxyl equivalent weights less than that of theproduct of the polymerization. Such a polyether starter may have, forexample, a hydroxyl equivalent weight of at least 125 and up to 6000, upto 4000, up to 2500, up to 1750, up to 1500, up to 1000, up to 500, orup to 250 g/equivalent. In some embodiments, the polyether starter maybe a homopolymer of propylene oxide and/or a random or block copolymerof propylene oxide and one or more other alkylene oxides (especiallyethylene oxide), which has a hydroxyl equivalent weight as mentioned inthis paragraph and in which no more than 25%, no more than 15% or nomore than 10% of the hydroxyl groups are primary.

In some embodiments, the aluminum compound is soluble in the starter atthe proportions present at the start of the polymerization. Solubilityis evaluated by combining the aluminum compound with the starter at theappropriate proportions and stirring at up to 160° C., preferably up to75° C., for 15 minutes. The formation of a clear fluid upon visualinspection indicates that the aluminum compound is soluble in thestarter.

Similarly, in some embodiments, the cyclic amidine is soluble in thestarter at the proportions present at the start of the polymerization,solubility being evaluated in the manner just described with regard tothe aluminum compound. Preferably, both the aluminum compound and cyclicamidine are soluble in the starter in the proportions present at thestart of the polymerization.

The alkylene oxide(s) may be, for example, ethylene oxide, 1,2-propyleneoxide (generally referred to herein as “propylene oxide”), oxetane,1,2-butene oxide, 2-methyl-1,2-butaneoxide, 2,3-butane oxide,tetrahydrofuran, epichlorohydrin, hexene oxide, octene oxide, styreneoxide, divinylbenzene dioxide, a glycidyl ether such as Bisphenol Adiglycidyl ether, epichlorohydrin or other polymerizable oxirane. Insome embodiments, the alkylene oxide is 1,2-propylene oxide, ethyleneoxide, or a mixture of at least 50% (preferably at least 80%) by weightpropylene oxide and correspondingly up to 50% (preferably up to 20%) byweight ethylene oxide. In some embodiments, two or more alkylene oxidesare polymerized simultaneously (to form random copolymers), and or thecomposition of the alkylene oxide is changed one or more times, or evencontinuously, throughout the course of the polymerization to form blockand/or random/block copolymers.

In specific embodiments, the starter is a poly(propylene oxide) orrandom propylene oxide/ethylene oxide copolymer containing at least 50%or at least 70% by weight oxypropylene units and up to 50% or up to 30%ethylene oxide units, and the alkylene oxide is ethylene oxide. In suchembodiments, the starter may have a hydroxyl equivalent weight of, forexample, 500 to 3000, 500 to 2500 or 500 to 1750 g/equivalent. In suchembodiments, the starter may be produced in the presence of an aluminumcompound and cyclic amidine in accordance with the invention and theethoxylation of the starter may take place without further addition ofaluminum compound and cyclic amidine, i.e., in the presence of the samealuminum compound and cyclic amidine as was used to alkoxylate prior tothe start of the final ethoxylation step, and/or without any step ofneutralization, catalyst removal or catalyst deactivation after thestarter is produced and before the ethoxylation step.

The polymerization is performed by combining the starter, aluminumcompound and cyclic amidine with the alkylene oxide(s) and optionallycomonomer and then polymerizing the alkylene oxide(s). It is oftenconvenient to combine at least a portion of the starter with at leastpart of the aluminum compound and at least part of the cyclic amidineprior to contacting the aluminum catalyst and cyclic amidine with thealkylene oxide. The polymerization proceeds at a wide range oftemperatures from −100° C. to 250° C. or more. In some embodiments, thereaction temperature is at least 80° C., at least 100° C., at least 120°C. or at least 130° C. The polymerization temperature preferably doesnot exceed 190° C., and more preferably does not exceed 180° C. Thepolymerization reaction usually is performed at a superatmosphericpressure, but can be performed at atmospheric pressure or even asubatmospheric pressure.

Enough of the aluminum compound is used to provide a commerciallyreasonable polymerization rate, but it is generally desirable to use aslittle of the aluminum compound as possible consistent with reasonablepolymerization rates, as this both reduces the cost for the catalyst andcan eliminate the need to remove catalyst residues from the product. Theamount of aluminum compound may be, for example, sufficient to provide10 to 10,000 ppm of aluminum based on the weight of the alkylene oxidepolymer or copolymer product of the polymerization. In specificembodiments, the amount of aluminum compound may be sufficient toprovide at least 25 ppm, at least 50 ppm, at least 100 ppm or at least250 ppm aluminum on the foregoing basis, and up to 5,000 ppm up to 2,500ppm, up to 1500 ppm or up to 1000 ppm aluminum, again on the foregoingbasis.

The amount of aluminum compound may be sufficient to provide, forexample, at least 0.00005 moles of aluminum, at least 0.00075 moles ofaluminum or at least 0.0001 moles of aluminum per equivalent of starter,and may be, for example, sufficient to provide up to 0.10 moles ofaluminum, up to 0.075 moles of aluminum, up to 0.06 moles of aluminum,up to 0.05 moles of aluminum or up to 0.025 moles of aluminum perequivalent of starter.

The mole ratio of aluminum compound to cyclic amidine may be, forexample, 1:10 to 10:1. A preferred ratio is at least 1:3, at least 1:2or at least 2:3, and up to 5:1, up to 4:1, up to 3:1, up to 2.5:1, up to2:1, up to 3:2, up to 4:3 or up to 1:1. The optimum ratio may vary amongspecific aluminum compound/cyclic amidine pairings. For example, whenthe aluminum compound is a trialkyl aluminum, the amount of cyclicamidine is preferably no greater than 0.75 mole per mole of aluminumcompound.

The amount of cyclic amidine may be, for example, at least 0.00005moles, at least 0.0001 mole or at least 0.0002 moles per equivalent ofstarter, and may be, for example, up to 0.10 mole, up to 0.075 moles, upto 0.06 mole, up to 0.05 mole or up to 0.025 mole per equivalent ofstarter.

Specific pairings of aluminum compound and cyclic amidine include:

Diethylaluminum chloride (Et₂AlCl) and DBU, Me-TBD or TBD. The moleratio of these may be, for example, 1:2 to 4:1, especially 2:3 to 2:1;

Et₂AlCl and DBN. The mole ratio of these may be, for example, 1:2 to4:1, especially >1:1 to 2:1;

Ethylaluminum dichloride (EtAlCl₂) and DBU or DBN. The mole ratio ofthese maybe, for example, 1:2 to 4:1, especially >1:1 to 2:1;

EtAlCl₂ and Me-TBD or TBD. The mole ratio of these may be, for example,1:2 to 4:1, especially 2:3 to 2:1;

DIBAL and DBU, Me-TBD or DBN. The mole ratio of these may be, forexample, 1:2 to 4:1, especially 2:3 to 2:1;

DIBAL and TBD. The mole ratio of these may be, for example, 1:4 to 5:1,especially 1:2 to 4:1;

(iBu)₂AlCl or Al(BHT)₂Me and DBU, Me-TBD, DBN or TBD. The mole ratio ofthese may be, for example, 1:4 to 4:1, especially 1:2 to 4:1;

TEDA with DBU, Me-TBD or DBN. The mole ratio of these may be, forexample, 1:2 to 4:1, especially 2:3 to 2:1;

TEDA with TBD. The mole ratio of these may be, for example, 1:6 to 4:1,especially 1:5 to 3:1;

a trialkyl aluminum compound, particularly one or more of trimethylaluminum, triethyl aluminum, triisopropyl aluminum, tri(n-propyl)aluminum, triisobutyl aluminum, tri(n-butyl)aluminum,tri(t-butyl)aluminum, tri(octadecyhaluminum, and one or more of DBU,Me-TBD, DBN or TBD. The mole ratio of these may be, for example, 1:2 to4:1, especially 2:3 to 4:1 or 1:2 to 3:1.

The polymerization reaction can be performed batch-wise,semi-continuously (including with continuous addition of starter asdescribed in U.S. Pat. No. 5,777,177) or continuously.

In a batch polymerization, the aluminum compound, cyclic amidine,starter, alkylene oxide(s) and optional comonomer are combined to form areaction mixture, and the reaction mixture is heated in a reactionvessel to the polymerization temperature until the desired molecularweight is obtained. A preferred manner of performing the batchpolymerization is to dissolve the aluminum compound and cyclic amidineinto the starter, then combine the resulting solution with the alkyleneoxide, followed by subjecting the resulting mixture to polymerizationconditions until the desired molecular weight is obtained and/or thealkylene oxide is consumed. The aluminum compound, the cyclic amidine,or both may be introduced in the form of a solution in an inert solventsuch as a hydrocarbon like toluene or hexane.

In a semi-batch process, the aluminum compound, cyclic amidine andstarter are combined, preferably by dissolving the catalyst and cyclicamidine into the starter. A polyether monol or polyether polyolcorresponding to the product of the polymerization, and/or a polyetherof intermediate molecular weight between that of the starter andproduct, may be combined with the starter if desired. The contents ofthe vessel are heated if necessary to the polymerization temperature anda portion of the alkylene oxide is introduced into the reaction vessel.When polymerization begins (typically as indicated by a drop of internalreactor pressure), more alkylene oxide is fed to the reactor underpolymerization conditions. The alkylene oxide feed is continued untilenough has been consumed to reach the target product molecular weight.Additional aluminum compound and/or cyclic amidine may be added duringthe course of the alkylene oxide addition. In a semi-batch process, theentire amount of starter is commonly added at the start of the process.After the alkylene oxide feed is completed, the reaction mixture may becooked down at the polymerization temperature to consume any remainingalkylene oxide.

A continuous polymerization includes the continuous or intermittentaddition of at least alkylene oxide and starter, and continuous orintermittent removal of product during the polymerization. A continuousprocess is generally conducted by establishing steady-stateconcentrations (within the operational capabilities of thepolymerization equipment) of the aluminum compound (or reaction productsthereof), the cyclic amidine, starter (or reaction products thereof),alkylene oxide and polymerizate under polymerization conditions in acontinuous reactor such as a loop reactor, a plug flow reactor, or acontinuous stirred tank reactor. The “polymerizate” is a mixture ofpolyethers that have molecular weights greater than that of the starterand up to that of the intended product. Additional aluminum compound,cyclic amidine, starter and alkylene oxide are then continuously addedto the reactor as the polymerization proceeds. These can be added as asingle stream, as separate components, or in various sub-combinations,but the aluminum compound and cyclic amidine are preferably added in theform of a solution in the starter. A product stream is continuously orintermittently withdrawn from the reactor during the polymerization. Therates of the additional stream(s) and product streams are selected tomaintain steady-state conditions in the reactor (within the operationalcapabilities of the equipment), and to produce a product having adesired molecular weight.

The product stream withdrawn from the continuous reactor may be cookeddown for some period of time to allow the unreacted alkylene oxide inthat stream to be consumed to low levels.

A continuous process is particularly suitable for producing a polyetherproduct having a hydroxyl equivalent weight from 150 to 5000, especiallyfrom 350 to 2500 and still more preferably from 500 to 2000g/equivalent.

In a semi-batch or continuous process as described above, the alkyleneoxide(s) may be fed to the reactor on demand by continuouslypressurizing the reactor with the alkylene oxide(s) to a predeterminedinternal reactor pressure and/or alkylene oxide partial pressure.

The polymerization reaction can be performed in any type of vessel thatis suitable for the pressures and temperatures encountered. In acontinuous or semi-continuous process, the vessel should have one ormore inlets through which the alkylene oxide and additional startercompound can be introduced during the reaction. In a continuous process,the reactor vessel should contain at least one outlet through which aportion of the partially polymerized reaction mixture can be withdrawn.A tubular reactor that has multiple points for injecting the startingmaterials, a loop reactor, and a continuous stirred tank reactor (CTSR)are all suitable types of vessels for continuous or semi-continuousoperations. The reactor should be equipped with a means of providingand/or removing heat, so the temperature of the reaction mixture can bemaintained within the required range. Suitable means include varioustypes of jacketing for thermal fluids, various types of internal orexternal heaters, and the like. A cook-down step performed oncontinuously withdrawn product is conveniently conducted in a reactorthat prevents significant back-mixing from occurring. Plug flowoperation in a pipe or tubular reactor is a preferred manner ofperforming such a cook-down step.

The crude product obtained in any of the foregoing processes may containup to 0.5% by weight, based on the total weight, of unreacted alkyleneoxide; small quantities of the starter compound and low molecular weightalkoxylates thereof; and small quantities of other organic impuritiesand water. Volatile impurities (including unreacted alkylene oxides)should be flashed or stripped from the product. The crude producttypically contains catalyst residues and residues of the aluminumcompound and/or cyclic amidine. It is typical to leave these residues inthe product, but these can be removed if desired. Moisture and volatilescan be removed by stripping the polyol.

The process of the invention is useful for preparing polyether polyolproducts that can have hydroxyl equivalent weights from as low as about85 to as high as about 8,000 or more.

The polymerization reaction can be characterized by the “build ratio”,which is defined as the ratio of the number average molecular weight ofthe polyether product to that of the starter compound. This build ratiomay be as high as 160, but is more commonly in the range of 2.5 to about65 and still more commonly in the range of 2.5 to about 50. The buildratio is typically in the range of about 2.5 to about 15, or about 7 toabout 11 when the polyether product has a hydroxyl equivalent weight of85 to 400 g/equivalent.

In some embodiments the alkylene oxide is polymerized with or in thepresence of one or more copolymerizable monomers that are not oxiranes.Examples of such copolymerizable monomers include carbonate precursorsthat copolymerize with an alkylene oxide to produce carbonate linkagesin the product. Examples of such carbonate precursors include carbondioxide, phosgene, linear carbonates and cyclic carbonates. Othercopolymerizable monomers include carboxylic acid anhydrides, whichcopolymerize with alkylene oxides to produce ester linkages in theproduct.

In some embodiments, polyether polyols of the invention are homopolymersof propylene oxide or random copolymers containing at least 50%, atleast 70% or at least 90% by weight oxypropylene units formed bypolymerizing propylene oxide and correspondingly up to 50%, up to 30% orup to 10% by weight oxyethylene units formed by polymerizing a mixtureof propylene oxide and ethylene oxide (in each case without the presenceof a copolymerizable monomer that is not an oxirane), having any one ormore of the following characteristics:

a) hydroxyl equivalent weight of at least 500, at least 750, at least1000 or at least 1200, and up to 4000, up to 3000, up to 2500, up to2200 or up to 2000 g/equivalent;

b) nominal hydroxyl functionality of 2 to 8;

c) no more than 0.015, no more than 0.01, no more than 0.007 meq/g ofterminal unsaturation;

d) a polydispersity (Mw/Mn) by gel permeation chromatography of no morethan 1.15, no more than 1.10, no more than 1.07 or no more than 1.05;

e) no more than 2000 parts by million by weight (ppm), no more than 1200ppm, no more than 1000 ppm, no more than 750 ppm, no more than 500 ppm,no more than 250 ppm, no more than 100 ppm or no more than 50 ppm, basedon polyether polyol weight, of a fraction having a molecular weight byGPC of 40,000 g/mol or more; and

f) no more than 12%, no more than 10%, no more than 8%, no more than 6%or no more than 5% of the hydroxyl groups are primary hydroxyl groups asdetermined by ASTM D-4273 or equivalent method. The polyether productmay have all of features a)-f).

In specific embodiments, the polyether polyol is a propylene oxidehomopolymer or random copolymer of a mixture of at least 85% or at least90% by weight propylene oxide and correspondingly up to 15% or up to 10%by weight ethylene oxide, based on the combined weight of all alkyleneoxides, the polyether polyol in each case without the presence of acopolymerizable monomer that is not an oxirane; and the polyether polyola) has a hydroxyl equivalent weight of 1000 to 2500 g/equivalent, b) hasa nominal functionality of 2 to 8; c) has no more than 0.007 meq/g ofterminal unsaturation; d) has a polydispersity (M_(w)/M_(n)) of no morethan 1.07 and preferably no more than 1.05; and e) contains no more than1200 ppm, no more than 1000 ppm, no more than 250 ppm or no more than 50ppm of a fraction having a molecular weight by GPC of 40,000 g/mol ormore. In addition, no more than 12%, no more than 10%, no more than 8%,no more than 6% or no more than 5% of the hydroxyl groups of such apolyether may be primary hydroxyl groups.

Polyether polyols produced in accordance with the invention are usefulfor making polyurethanes, among other things. Higher equivalent weight(500-8000 g/equivalent) polyether polyol products are useful in makingelastomeric or semi-elastomeric polyurethane, including noncellular ormicrocellular elastomers, and flexible polyurethane foams. The flexiblepolyurethane foams may be made in a slabstock or molding process.Polyether polyol products having equivalent weights of about 225 to 400are useful in making semi-flexible foams as well as the so-calledviscoelastic or “memory” foams. Polyether polyols having equivalentweights of 85 to 400 are useful in making rigid polyurethane foams, suchas thermal insulating foams for appliances, buildings, ship hulls andthe like, as well as in various coating, adhesive, sealant and elastomerproducts. The polyether polyols tend to have properties quite similar tothose made in conventional DMC-catalyzed polymerization process and inalkali metal hydroxide-catalyzed polymerization processes.

Polyether monols produced in accordance with the invention are useful assurfactants or as industrial solvents, among other uses.

The following examples are provided to illustrate the invention but arenot intended to limit the scope thereof. All parts and percentages areby weight unless otherwise indicated.

Catalyst Preparation Procedure

The starter is heated at 70° C. and purged with nitrogen and/or passedthrough a plug of alumina before use. 20 g of starter is transferred toa 50-mL glass jar. Under nitrogen, the indicated amounts of aluminumcompound and cyclic amidine (if any) are combined with the starter. Thejar is capped and its contents stirred for approximately 20 minutes. Ifthe resulting mixture appears heterogeneous, the contents of the jar areheated at 70° C. for 5-10 additional minutes with continued stirring,and then cooled.

Parallel Pressure Reactor (PPR) Polymerization Procedure

Alkylene oxide polymerizations and/or propylene oxide oxide/carbondioxide copolymerizations are performed on using a 48-well SymyxTechnologies Parallel Pressure Reactor (PPR). Each of the 48 wells isequipped with an individually weighed glass insert having an internalworking liquid volume of approximately 5 mL. The wells each contain anoverhead paddle stirrer.

0.7 mL of the starter/catalyst/cyclic amidine mixture (containingapproximately 0.72 g of the starter) is charged to each insert. Eachwell is pressurized with 50 psig (344.7 kPa) of nitrogen and then heatedto the polymerization temperature. Upon reaching the polymerizationtemperature 1 mL of the epoxide is injected into each well, where itreacts with the starter in the glass insert.

The internal pressure in the headspace of each well is monitoredindividually throughout the polymerization. Each hour after the firstinjection of epoxide, the internal pressure is observed, and if thepressure in any particular well has fallen below 190 psig (1.31 MPa),another 1 mL of the alkylene oxide is injected. This is repeated up tothree times throughout the entire length of the run, which is 4 hours. 4hours after the first epoxide injection, the wells are allowed to coolto room temperature and vented. The glass inserts are allowed to standunder nitrogen at 40-50° C. overnight to allow residual epoxide tovolatilize, after which the inserts are weighed to determine the amountof product.

The resulting products are analyzed for molecular weight andpolydispersity (M_(w)/M_(n)) by gel permeation chromatography against apolystyrene standard. Primary hydroxyl content is determined byfunctionalizing the product with trifluoroacetic anhydride andevaluating the resulting product by ¹⁹F NMR spectroscopy, per a standardmethod such as ASTM D-4273.

EXAMPLES 1-6 AND COMPARATIVE SAMPLE A

In these polymerizations, the starter is a 700 molecular weight,trifunctional poly(propylene oxide) and the aluminum compound isdiethylaluminum chloride (Et₂AlCl). The amount of aluminum compound ineach case is 2000 parts per million based on the weight of the starter(ppm). The mole ratio of aluminum compound to the cyclic amidineinitially present is as indicated in Table 1; this ratio is also themole ratio of aluminum atoms to cyclic amidine. The polymerizationtemperature is 160° C. The cyclic amidine is diazabicycloundecene (DBU),methyl-triazabicyclodecene (Me-TBD), 1,8-diazabicyclo-7-undecene (DBN)or triazabicyclodecene (TBD), as indicated in Table 1, as are the amountof product produced, the % of hydroxyl groups that are primary, thenumber average molecular weight and the polydispersity (PDI,M_(w)/M_(n)).

TABLE 1 PO Polymerizations with Et₂AlCl Al:cyclic ppm Al Cyclic amidineYield, %1° Sample compound amidine ratio¹ g OH PDI M_(n) Comp. 2000 NoneN/A 1.50 7 1.08 1636 A* Ex. 1 2000 DBU 1:1 3.09 4 1.03 3865 Ex. 2 2000Me- 1:1 2.67 5 1.03 3233 TBD Ex. 3 2000 DBN 1:1 0.99 5 1.03 1064 Ex. 42000 TBD 1:2 0.80 8 1.03 942 Ex. 5 2000 TBD 1:1 3.04 5 1.03 3829 Ex. 62000 TBD 2:1 2.39 4 1.04 2761 *Comparative. ¹Mole ratio, aluminumcompound to cyclic amidine.

DBU and Me-TBD, at a mole ratio of 1:1 relative to the aluminumcompound, provides a large increase in polymerization rate and productmolecular weight, compared with the control which lacks any cyclicamidine compound. DBN at the same level provides no such increase atthis particular ratio of Et₂AlCl:DBN; better results are expected at ahigher ratio, as suggested by the results with TBD (Examples 4-6).Examples 4-6 demonstrate the effect of Al:cyclic amidine ratio with TBD.A lower ratio (i.e., high relative amount of TBD), as in Ex. 4, appearsto suppress catalytic activity, leading to a lower yield. Ratios of 1:1and 2:1 lead to very large increases in both yield and product molecularweight.

EXAMPLES 7-13 AND COMPARATIVE SAMPLE B

In these polymerizations, the starter is a 700 molecular weight,trifunctional polypropylene oxide), the alkylene oxide is propyleneoxide and the aluminum compound is ethylaluminum dichloride (EtAlCl₂).The amount of aluminum compound in each case is as indicated in Table 2.The mole ratio of aluminum compound to the cyclic amidine in each caseis as indicated in Table 2; this ratio is also the mole ratio ofaluminum atoms to cyclic amidine in each case. The polymerizationtemperature is 160° C. The cyclic amidine is as indicated in Table 2, asare the amount of product produced, the % of hydroxyl groups that areprimary, the number average molecular weight and the polydispersity(PDI, M_(w)/M_(n)).

TABLE 2 PO Polymerizations with EtAlCl₂ Al:cyclic ppm Al Cyclic amidineYield, %1° Sample compound amidine ratio¹ g OH PDI M_(n) Comp. 2000 NoneN/A 1.41 33  1.06 1669 B* Ex. 7 2000 DBU 1:1 1.29 5 1.04 1570 Ex. 8 2100DBN 1:1 0.88 4 1.03 1029 Ex. 9 2100 Me- 1:1 2.98 5 1.03 3145 TBD Ex. 102100 TBD 1:2 0.82 ND ND ND Ex. 11 2100 TBD 1:1 2.84 5 1.03 3404 Ex. 122100 TBD 2:1 2.99 5 1.08 3544 Ex. 13 2100 TBD 4:1 0.73 4 1.07  871*Comparative. ND—not done. ¹Mole ratio, aluminum atoms to cyclicamidine.

At a mole ratio of 1:1, DBU and DBN do not increase yield or productmolecular weight compared to the case in which no cyclic amidinecompound is present. The data using TBD (Ex. 10-13) suggest that DBU andDBN will provide benefits at higher ratios of aluminum atoms to DBU orDBN. Me-TBD provides a large increase in yield even when present at the1:1 mole ratio. Examples 10-13 again demonstrate the sensitivity ofaluminum to TBD ratio. Excellent results are seen at the 1:1 and 2:1ratios, but only small yields and low product molecular weights areobtained at the 1:2 and 4:1 ratios.

EXAMPLES 14-20 AND COMPARATIVE SAMPLE C

Polymerizations are performed in the same general manner as in theprevious examples, using various cyclic amidines as indicated in Table3. The aluminum compound is diisobutyl aluminum hydride (DIBAL). Themole ratio of DIBAL to the cyclic amidine is as indicated in Table 3, asare the amount of DIBAL and the results. The mole ratio of DIBAL to thecyclic amidine is also the mole ratio of aluminum atoms to cyclicamidine in each case.

TABLE 3 PO Polymerizations with DIBAL Al:cyclic Al ppm Al Cyclic amidineYield, %1° Sample compound compound amidine ratio¹ g OH PDI M_(n) Comp.C* DIBAL 2000 None N/A 1.19 31 1.06 1392 Ex. 14 DIBAL 2350 DBN 1:1 1.915 1.03 2214 Ex. 15 DIBAL 2350 Me-TBD 1:1 2.02 5 1.03 2332 Ex. 16 DIBAL2350 DBU 1:1 2.66 5 1.02 3016 Ex. 17 DIBAL 2100 TBD 1:2 1.60 5 1.08 1860Ex. 18 DIBAL 2100 TBD 1:1 2.85 5 1.07 3431 Ex. 19 DIBAL 2100 TBD 2:12.52 7 1.08 2894 Ex. 20 DIBAL 2100 TBD 4:1 1.78 10 1.08 2011*Comparative. ¹Mole ratio, aluminum compound to cyclic amidine.

All of the cyclic amidines provide increases in yield and productmolecular weight when used with DIBAL. The data with TBD indicates thatDIBAL:cyclic amidine combinations are less sensitive to DIBAL:cyclicamidine ratio than are some other aluminum compounds, although bestresults are still seen at the 1:1 and 2:1 ratios.

EXAMPLES 21-24 AND COMPARATIVE SAMPLES D-F

Polymerizations are performed in the same general manner as in theprevious examples, using various aluminum compounds as indicated inTable 4, in combination with TBD. The aluminum compounds aredi(isobutyl)aluminum chloride (iBu₂AlCl),

The mole ratio of aluminum compound to the cyclic amidine is asindicated in Table 4, as are the amount of aluminum compound and theresults. The mole ratio of aluminum compound to the cyclic amidine isalso the mole ratio of aluminum atoms to cyclic amidine in each case.

TABLE 4 PO Polymerizations Using Various Al Compounds and TBD Al:cyclicAl ppm Al Cyclic amidine Yield, %1° Sample compound Compound amidineratio¹ g OH PDI M_(n) Comp. D* (iBu)₂AlCl 2950 None N/A 1.68 16  1.051846 Ex. 21 (iBu)₂AlCl 2950 TBD 1:1 2.75 4 1.03 3281 Comp. E* Al(BHT)₂Me2000 None N/A 0.83 ND 1.04 1045 Ex. 22 Al(BHT)₂Me 2000 TBD 1:1 1.27 61.03 1568 Ex. 23 Al(OiPrPh)₂Me 6600 TBD 1:1 2.00 ND 1.03 2361 Comp. F*Al(OtriPh)₂Me 8850 None N/A 1.41 ND 1.06 1592 Ex. 24 Al(OtriPh)₂Me 8850TBD 1:1 2.75 ND 1.03 3352 *Comparative. ND—not done. ¹Mole ratio,aluminum compound to cyclic amidine.

In each case, the addition of TBD leads to a large increase in yield andproduct molecular weight.

EXAMPLES 25-32 AND COMPARATIVE SAMPLE G

Polymerizations are performed in the same general manner as in theprevious examples, using tetraethyldialuminoxane (TEDA) in combinationwith various cyclic amidines as indicated in Table 5. The mole ratio ofTEDA to the cyclic amidine is as indicated in Table 5, as are the amountof TEDA and the results. Because TEDA contains two aluminum atoms, themole ratio of aluminum atoms to cyclic amidine in each case is doublethe mole ratio of TEDA to the cyclic amidine reported in Table 5.

TABLE 5 PO Polymerizations Using TEDA Al:cyclic Al ppm Al Cyclic amidineYield, %1° Sample compound compound amidine ratio¹ g OH PDI M_(n) Comp.G* TEDA 3100 None N/A 1.47 36  1.06 1657 Ex. 25 TEDA 1550 DBN 1:1 3.04 51.03 3361 Ex. 26 TEDA 1550 Me-TBD 1:1 0.80 4 1.03  971 Ex. 27 TEDA 1550DBU 1:1 2.79 5 1.03 3206 Ex. 28 TEDA 1550 TBD 1:8 0.84 ND ND ND Ex. 29TEDA 1550 TBD 1:4 2.06 ND 1.03 2556 Ex. 30 TEDA 1550 TBD 1:2 2.91 5 1.033579 Ex. 31 TEDA 1550 TBD 1:1 2.79 6 1.03 3357 Ex. 32 TEDA 1550 TBD 2:12.45 9 1.04 2831 *Comparative. ND—not done. ¹Mole ratio, aluminumcompound to cyclic amidine.

The combination of TEDA with DBN, DBU and TBD provides a large increasein yield and molecular weight, compared to the case of TEDA by itself.Me-TBD does not lead to such increases at the 1:1 ratio evaluated, butis expected to provide yield and molecular weight increases at differentratios of TEDA to Me-TBD. At very low TEDA-TBD ratios, as in Example 28,the TBD has little effect on yield or molecular weight, but otherwisethe TEDA/TBD combination exhibits a large positive effect over a rangeof TEDA:TBD ratios.

EXAMPLES 33-42

Various combinations of aluminum compound and cyclic amidine areevaluated in propoxylations of small molecule starters. The starters areglycerin, sorbitol, ortho-toluene diamine (oTDA), and bis(3-aminopropyl)methyl amine (BAPMA). The cyclic amidine is TBD in all cases. The moleratio of aluminum compound to TBD is 1:1 in all cases; the mole ratio ofaluminum atoms to cyclic amidine is also 1:1. Polymerizations areperformed in the same general manner as in the previous examples. Thealuminum compound is as indicated in Table 6, as are the results of thepolymerizations.

TABLE 6 PO Polymerizations from Small Molecules Using TBD Starter Al ppmAl molecular Yield, Sample compound compound Starter weight g PDI M_(n)Ex. 33 Et₂AlCl 2000 glycerin 92 1.73 1.06 304 Ex. 34 EtAlCl₂ 2000glycerin 92 1.75 1.07 302 Ex. 35 Al(BHT)₂Me 8000 glycerin 92 1.74 1.06308 Ex. 36 Et₂AlCl 2000 sorbitol 182 1.37 1.05 462 Ex. 37 EtAlCl₂ 2000sorbitol 182 1.28 1.05 462 Ex. 38 Al(BHT)₂Me 8000 sorbitol 182 1.48 1.05439 Ex. 39 Et₂AlCl 2000 oTDA 122 2.47 1.01 377 Ex. 40 EtAlCl₂ 2000 oTDA122 2.57 1.01 374 Ex. 41 Et₂AlCl 2000 BAPMA 142 2.19 1.07 337 Ex. 42EtAlCl₂ 2000 BAPMA 142 2.19 1.06 330

As demonstrated by the data in Table 4, the combination of variousaluminum compounds with TBD results in the effective propoxylation ofvarious low molecular weight hydroxyl-containing and amine-containingstarters. As before, polydispersity remains low.

EXAMPLES 43-45 AND COMPARATIVE SAMPLES H-J

Various combinations of aluminum compound and TBD are evaluated inethoxylations of the 700 molecular weight triol starter described inprevious examples. The ethoxylations are performed with and without TBD.The mole ratio of aluminum compound to TBD is 1:1 in all cases in whichTBD is present; the mole ratio of aluminum atoms to cyclic amidine isalso 1:1 in those cases. Polymerizations are performed in the samegeneral manner as in the previous examples. The aluminum compound is asindicated in Table 7, as are the results of the polymerizations.

TABLE 7 EO Polymerizations Using TBD ppm Cyclic Yield, %1° SampleCatalyst catalyst amidine g OH PDI M_(n) Comp. Et₂AlCl 2000 None 1.1160  1.11 1293 H* Ex. 43 Et₂AlCl 2000 TBD 2.69 4 1.07 3641 Comp. EtAlCl₂2000 None 1.03 ND 1.07 1400 I* Ex. 44 EtAlCl₂ 2000 TBD 2.59 5 1.07 3508Comp. Al(BHT)₂Me 8000 None 1.02 35  1.07 1360 J* Ex. 45 Al(BHT)₂Me 8000TBD 2.37 ND 1.06 3253 *Comparative. ND is not determined.

The data in Table 7 shows that ethylene oxide is successfullypolymerized onto a 700 molecular weight triol starter using an aluminumcatalyst/cyclic amidine system.

Comparative Samples K-Q

PO polymerizations are performed in the same general manner as in theprevious examples, using AlCl₃ or tris(diisopropoxylaluminum) phosphate(TDIPAP) as the aluminum compound in combination with TBD. The moleratio of aluminum compound to TBD is as indicated in Table 8, as are theamount of aluminum compound and the results.

TABLE 8 PO polymerizations Using AlCl₃ or Tri(diisopropylaluminum)phosphate Al Al ppm Al compound:TBD Sample compound compound ratio¹Yield, g Comp. K* AlCl₃ 2000 N/A 0.79 Comp. L* AlCl₃ 2000 2:1 0.75 Comp.M* AlCl₃ 2000 1:1 0.76 Comp. N* AlCl₃ 2000 1:2 0.74 Comp. O* TDIPAP 2950N/A 1.02 Comp. P* TDIPAP 2950 1:1 1.05 Comp. Q* TDIPAP 2950 1:3 0.86*Comparative. ¹Mole ratio, aluminum compound to TBD.

Low yields are obtained in each case despite the presence of TBD, whichis shown above to provide enhanced polymerization rates when used inconjunction with other aluminum catalysts.

EXAMPLES 46-57 AND COMPARATIVE SAMPLES R AND S

Larger-scale propoxylations of the 700 molecular weight triol starterare performed in a semi-batch reactor using various aluminum compoundsand TBD as the cyclic amidine. The cyclic amidine is omitted in Comp.Sample R. The aluminum compound:cyclic amidine molar ratio in each ofExamples 46-53 and 55-57 is 1:1; this ratio is 2:1 for Example 54.

The amount of PO fed, the run time and yield are indicated in Table 9,together with the % primary hydroxyl groups, polydispersity and M. ofthe product. Less PO is fed in Comparative Samples R and S and inExample 47 due to slow rates of polymerization.

TABLE 9 PO partial Al ppm Al Cyclic pressure PO fed Run Time Yield %1Sample compound Compound amidine (psi) (mL) (hr) (g) OH PDI M_(n) R*TEDA 1555 None 30 34 19.6 56 ND 1.04 1356 46 TEDA 1555 TBD 30 164 11.3157 ND 1.03 3633 47 Al(BHT)₂Me 8000 TBD 8 98 62.2 109 ND 1.04 2477 48Al(BHT)₂Me 8000 TBD 20 164 13.5 165 6 ND ND 50 Al(BHT)₂Me 8000 TBD 30164 12.8 161 ND 1.04 3647 51 Et₂AlCl 2000 TBD 20 164 19.5 163 5 1.033612 52 EtAlCl₂ 2000 TBD 20 164 24.5 158 ND 1.04 3512 53 AlMe₃ 1200 TBD30 164 15.2 157 ND 1.03 3544 54 AlMe₃ 1200 TBD** 30 164 11.5 158 ND 1.033594 S* AlEt₃ 1900 None 30 100 22.4 106 22  1.12 2035 55 AlEt₃ 1900 TBD30 164 26.6 153 7 1.03 3463 56 AlEt₃ 1900 DBU 30 164 12.8 161 4 1.033707 57 AlEt₃ 1900 MTBD 30 164 8.4 160 4 1.03 3749 *Comparative.**Aluminum catalyst:TBD mole ratio is 2:1 in this example; the moleratio of Al compound to cyclic amidine is 1:1 for all other examples.

Large increases in yield and molecular weight are again seen in thesesemi-batch polymerizations when the cyclic amidine is present.Polydispersity and the proportion of primary hydroxyl groups each arequite low. The results with AlMe₃ and AlEt₃ are particularly surprisingin that low proportions of primary hydroxyl groups are obtained.Trialkyl aluminum catalysts by themselves are known to be poorlystereospecific, promoting both the head-to-tail and head-to-headpolymerizations of propylene oxide. This phenomenon is illustrated byComparative Sample S, in which 22% of the hydroxyl groups are primary.Including the cyclic amidine not only increases yield and molecularweight but also promotes greater stereospecificity, yielding a producthaving a low proportion of primary hydroxyl groups.

1. A method for producing an alkylene oxide polymer or copolymer,comprising combining (i) at least one aluminum compound containing atleast one trisubstituted aluminum atom, wherein at least one of thesubstituents of at least one trisubstituted aluminum atom ishydrocarbyl; (2) at least one cyclic amidine; (3) at least one starter;(4) at least one alkylene oxide and optionally (5) at least onecomonomer that is not an oxirane, and polymerizing the alkylene oxide(s)or copolymerizing the alkylene oxide(s) and optionally the comonomer toform the alkylene oxide polymer or copolymer.
 2. The method of claim 1wherein at least one aluminum atom of the aluminum compound issubstituted with one or two hydrocarbyl groups, and is substituted withone or two halogen, oxo, ether or hydride groups.
 3. The method of claim1 wherein the aluminum compound includes one or more of trimethylaluminum, triethyl aluminum, triisopropyl aluminum, tri-n-propylaluminum, triisobutyl aluminum, tri-n-butyl aluminum,tri-t-butylaluminum and trioctadecylaluminum.
 4. The method of claim 1wherein the aluminum compound includes one or more of dimethyl aluminumchloride, methyl aluminum dichloride, diethyl aluminum chloride, ethylaluminum dichloride, diisobutyl aluminum chloride, isobutyl aluminumdichloride, methyl aluminum di[(2,6-di-t-butyl-4-methyl)phenoxide](Al(BHT)₂Me), dimethyl 2,6-di-t-butyl-4-methylphenoxide (AlBHTMe₂)methyl aluminum di(2,6-diisopropyl)phenoxide, dimethyl aluminum(2,6-diisopropyl)phenoxide methyl aluminum di [(2,6-diphenyl)phenoxide], dimethyl aluminum (2,6-diphenyl) phenoxide, methyl aluminumdi[(2,4,6-trimethyl)phenoxide], dimethyl aluminum(2,4,6-trimethyl)phenoxide, tetraethylaluminane, tetramethylaluminane,diisobutyl aluminum hydride, isobutyl aluminum dihydride, dimethylalumimum hydride, methyl aluminum dihydride, diethyl aluminum hydride,ethyl aluminum dihydride, diisopropyl aluminum hydride, isopropylaluminum dihydride, diethyl aluminum ethoxide, ethyl aluminumdiethoxide, dimethyl aluminum ethoxide, methyl aluminum diethoxide,dimethyl aluminum fluoride, methyl aluminum difluoride, diethyl aluminumfluoride, ethyl aluminum difluoride, diisobutyl aluminum fluoride,isobutyl aluminum difluoride, dimethyl aluminum bromide, methyl aluminumdibromide, diethyl aluminum bromide, ethyl aluminum dibromide,diisobutyl aluminum bromide, isobutyl aluminum dibromide, dimethylaluminum iodide, methyl aluminum diiodide, diethyl aluminum iodide,ethyl aluminum diiodide, diisobutyl aluminum iodide and isobutylaluminum iodide.
 5. The method of claim 1 wherein the aluminum compoundincludes a tetraalkylaluminoxane in which each alkyl group independentlycontains 1 to 6 carbon atoms.
 6. The method of claim 1 wherein thecyclic amidine is a bicyclic amidine.
 7. The method of claim 6 whereinthe bicyclic amidine is those represented by the structure:

wherein X is CHR or NR¹, wherein each R is independently hydrogen,unsubstituted or inertly substituted alkyl (including cycloalkyl),unsubstituted or inertly substituted phenyl or a non-protic nucleophilicgroup and each R¹ is independently hydrogen, hydrocarbyl or inertlysubstituted hydrocarbyl, and m and n are each independently a positiveinteger.
 8. The method of claim 6 wherein the bicyclic amidine is one ormore of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD),5-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (Me-TBD)1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) and6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, where the butylgroups are independently n-butyl, sec-butyl or t-butyl groups.
 9. Themethod of claim 1 wherein the cyclic amidine is imidazole or animidazole derivative corresponding to the structure:

wherein R³ and each R⁴ is independently hydrogen, unsubstitutedhydrocarbyl or inertly substituted hydrocarbyl.
 10. The method of claim9 wherein the cyclic amidine is one or more of imidazole, N-methylimidazole, N-ethyl imidazole, N-phenyl imidazole, 1,2-dimethylimidazole, 1,2-diethyl imidazole, 1,2-diphenyl imidazole, 4,5-dimethylimidazole, 4,5-diethylimidazole, 4,5-diphenyl imidazole, 1,4,5-trimethylimidazole, 1,4,5-triethyl imidazole, 1,4,5-triphenyl imidazole and thelike.
 11. The method of claim 1 wherein the aluminum compound is presentin an amount sufficient to provide 100 to 2,500 parts by weight ofaluminum per million parts by weight of the alkylene oxide polymer orcopolymer.
 12. The method of claim 1 wherein the aluminum compound andstarter are combined at a mole ratio of 0.00005 to 0.05 moles ofaluminum provided by the aluminum compound per mole of starter. 13.(canceled)
 14. The method of claim 1 wherein the aluminum compound andcyclic amidine are combined at a mole ratio of 1:2 to 4:1.
 15. Themethod of claim 1 wherein: the aluminum compound is diethylaluminumchloride and the cyclic amidine is DBU, Me-TBD or TBD, and the moleratio of the aluminum compound to the cyclic amidine is 2:3 to 2:1; thealuminum compound is diethylaluminum chloride and the cyclic amidine isDBN, and the mole ratio of the aluminum compound to the cyclic amidineis >1:1 to 2:1; the aluminum compound is ethylaluminum dichloride andthe cyclic amidine is DBU or DEM, and the mole ratio of the aluminumcompound to the cyclic amidine is >1:1 to 2:1; the aluminum compound isethylaluminum dichloride and the cyclic amidine is Me-TBD or TBD, andthe mole ratio of the aluminum compound to the cyclic amidine is 2:3 to2:1; the aluminum compound is DIBAL and the cyclic amidine is DBU,Me-TBD or DBN, and the mole ratio of the aluminum compound to the cyclicamidine is 2:3 to 2:1; the aluminum compound is DIBAL and the cyclicamidine is TBD, and the mole ratio of the aluminum compound to thecyclic amidine is 1:2 to 4:1; the aluminum compound is (iBu)₂AlCl orAl(BHT)₂Me and the cyclic amidine is DBU, Me-TBD, DBN or TBD, and themole ratio of the aluminum compound to the cyclic amidine is 1:2 to 4:1;the aluminum compound is TEDA and the cyclic amidine is DBU, Me-TBD orDBN, and the mole ratio of the aluminum compound to the cyclic amidineis 2:3 to 2:1; the aluminum compound is TEDA and the cyclic amidine isTBD, and the mole ratio of the aluminum compound to the cyclic amidineis 1:5 to 3:1 or the aluminum compound is one or more of trimethylaluminum, triethyl aluminum, triisopropyl aluminum, tri(n-propyl)aluminum, triisobutyl aluminum, tri(n-butyl)aluminum, tri(t-butyl)aluminum, tri(octadecyl)aluminum, and the cyclic amidine is one or moreof DBU, Me-TBD, DBN or TBD and the mole ratio of the aluminum compoundto the cyclic amidine is 2:3 to 4:1.
 16. (canceled)
 17. The method ofclaim 1 wherein the starter contains 2 to 8 hydroxyl groups and has anequivalent weight of 30 to
 250. 18. The method of claim 1 wherein thealkylene oxide is propylene oxide, ethylene oxide or a mixture ofpropylene oxide and ethylene oxide.
 19. The method of claim 1 whereinthe starter is a homopolymer of propylene oxide and/or a random or blockcopolymer of propylene oxide in which no more than 25% of the hydroxylgroups are primary, which starter has a hydroxyl equivalent weight of atleast 125 up to 1000 g/equivalent, and the alkylene oxide is ethyleneoxide.
 20. A polyether polyol being a homopolymer of propylene oxide orrandom copolymer of propylene oxide and ethylene oxide, the polyetherpolyol being prepared by homopolymerizing propylene oxide or a mixtureof at least 70% by weight propylene oxide and correspondingly up to 30%by weight ethylene oxide, based on the weight of alkylene oxidespolymerized, in the absence of any comonomer that is not an oxirane, toform the polyether polyol, characterized in that a) the polyether has ahydroxyl equivalent weight of at least 500 up to 4000 g/equivalent; b)the polyether has a nominal hydroxyl functionality of 2 to 8; c) thepolyether has no more than 0.01 meq/g of terminal unsaturation; d) thepolyether has a polydispersity (M_(w)/M_(n)) by gel permeationchromatography of no more than 1.10; e) the polyether contains no morethan 2000 parts by million by weight (ppm) based on polyether polyolweight, of a fraction having a molecular weight by GPC of 40,000 g/molor more; and f) no more than 12% of the hydroxyl groups of the polyetherare primary hydroxyl groups as determined by ASTM D-4273 or equivalentmethod, wherein at least 90% of the weight of the polyether isoxypropylene and/or oxyethylene units.
 21. A polyether polyol being apropylene oxide homopolymer or random copolymer of propylene oxide andethylene oxide, the polyether polyol being prepared by homopolymerizingpropylene oxide or a mixture of at least 90% by weight propylene oxideand correspondingly up to 10% by weight ethylene oxide, based on theweight of alkylene oxides polymerized, in the absence of any comonomerthat is not an oxirane, to form the polyether polyol, the polyetherpolyol being further characterized in a) having a hydroxyl equivalentweight of 1000 to 2500 g/equivalent, b) having a nominal functionalityof 2 to 8; c) having no more than 0.007 meq/g of terminal unsaturation;d) having a polydispersity (M_(w)/M_(n)) of no more than 1.07; and e)containing no more than 1200 ppm, of a fraction having a molecularweight by GPC of 40,000 g/mol or more, wherein at least 90% of theweight of the polyether is oxypropylene and/or oxyethylene units. 22.The polyether polyol of claim 21 wherein no more than 8% of the hydroxylgroups are primary hydroxyl groups.